Isocyanates of selected fluoroalkylimidazolines



United States Patent O ABSTRACT OF THE DISCLOSURE Described and claimedare iscoyanates of fluoroalkylimidazolines, e.g,4-isocyanato-2,2,5,5-tetrakis(trifluoromethyl)-3-imidazoline, useful formodifying polymers and as agents for waterproofing paper. The compoundsare prepared from oxalyl chloride and the corresponding4-amino-3-imidazoline or its tautomer.

This application is a continuation-impart of my coassigned copendingapplication Ser. No. 521,317, filed Feb. 9, 1966, as acontinuation-in-part of my copending application Ser. No. 461,151, filedJune 3, 1965, and now abandoned itself a continuation-in-part of mynowabandoned application Ser. No. 439,476, filed Mar. 12, 1965.

FIELD OF THE INVENTION This invention relates to, and has as itsprincipal objects provision of, isocyanates of certain selectedfluoroalkylimidazolines and the preparation of the same.

DETAILS OF THE INVENTION The new compounds of this invention are4-is0cyanato- 2,2,5,5 tetrakis(polyhalomethyl) 3-imidiazolines of thegeneral formula where Y Y Y and Y may be alike or diiferent and arehydrogen, chlorine or fluorine. These novel compounds are formed fromthe 4-amino-3-imidazoline compounds or their tautomers, the4-iminoimidazolidines, of the formula where the symbols are as definedabove, by reaction of the same with oxalyl chloride. The compounds ofFormulas HA and B exist in equilibrium, especially in solution, andreference to either form in this specification is to be understood asincluding the other.

The reaction between the amino compound and oxalyl chloride isaccomplished without solvent or in an inert solvent at ambient orslightly elevated temperatures, e.g, at the reflux temperature of thereaction mixture. Preferably, a one-to-one molar proportion of aminocompound and oxalyl chloride is employed although an excess of oxalylchloride will have no adverse effects. Essentially anhydrous conditionsshould be maintained throughout this process and traces of moisture inthe reactants, solvents, apparatus or in contact with the isocyanateproduct will lower the yield. Even moderate amounts of Water will not,however, make the process inoperable.

Any inert solvent, usually of RP. 25-100" C., may be used; ethers andparticularly diethyl ether, are preferred.

Higher boiling ethers such as dioxane, ethylene glycol dimeth'yl ether,and the like may be employed to advantage if the amino compound reactantis less reactive toward oxalyl chloride than usual. Other operablesolvents include: hydrocarbons, e.g., benzene, toluene, the xylenes; andchlorinated hydrocarbons, e.g, chloroform and chlorobenzene. An excessof oxalyl chloride can also be used to advantage as solvent.

Best results occur when the amino compound is added to the oxalylchloride so that an excess of the latter is present to prevent a sidereaction between the amino compound and the product isocyanate.Conveniently, the amino reactant is dissolved in the solvent and addeddropwise to a stirred solution of oxalyl chloride in the solvent. It ispreferred that the addition take at least 10 minutes, but this willdepend on the reaction scale. Time and temperature are not critical but0.5-2 hours at 25- C. are usually employed. The products are isolated byordinary techniques, e.g, distillation.

The compounds of Formula II used in preparing the isocyanates of thisinvention can be prepared by reacting three moles of an imine of theformula (III) NH wherein Y and Y have the meanings given above, with onemole of an alkali metal cyanide, e.g., sodium or potassium cyanide, at-40 to 100 C. to form a polyhalomethylethylimine-substitutedintermediate, followed by heating the intermediate to eliminate thepolyhalomethylethylirnine substituent. This heating is preferably donein an acid such as a mineral acid and preferably in concentratedsulfuric acid. If it is desired that Y and Y be different from the Y andY in the product being prepared, more than one polyhaloalkylideniminemust be employed in the reaction mixture and this will result in morethan one product being formed. The reaction of thepolyhaloalkylidenimine with the alkali metal cyanide is preferablycarried out in an inert reaction medium such as dimethylformamide;dimethyl sulfoxide; liquid nitriles, e.g, acetonitrile and benzonitrilc;glycol ethers, e.g., the dimethyl ethers of ethylene and diethyleneglycols; etc. This process is described in greater detail in myabovementioned application Ser. No. 521,317.

The imines of Formula III used as starting materials in theabove-described process can be prepared in various ways. Those in whichY and Y in the formula are fluotime or chlorine can be prepared as shownin my US. Pat ent No. 3,226,439 and in J. Org. Chem. 30, 1398 (1965).Those in which Y or Y or both, are: hydrogen, can be prepared by amodification of the method of Zeifman et al., Akad. nauk. S.S.S.R.Doklady, 153, 1334 (1963), for preparing hexafluoroisopropylidenirnine.The process for preparing pentafiuoroisopropylidenimine involves firstreacting pentafluoroacetone with phenyl isocyanate at about 200 C. inthe presence of a catalytic amount of a triarylphosphine oxide to formN-phenylpentafluoroisopropylidenimine, which is then treated withammonia to give N-phenyl-Z,2-diaminopentafluoropropane. This prodnot,which need not be isolated or purified prior to the next and last step,is then reacted with phosphorus pentoxide, whereby it splits olf anilinewith formation of pentafluoroisopropylidenimine (U.S. Pat. 3,342,864).

SPECIFIC EMBODIMENTS OF THE INVENTION There follow some nonlimitingexamples illustrating the invention in more detail. In carrying outthese examples, essentially anhydrous conditions were maintained.

Example 1.4 isocyanato 2,2,5,5 tetrakis(trifluoromethyl)-3-imidazolineNCO C (O FalzC N ClCOCOCl I l IINC(C Fgh A three-necked flask attachedto the bottom of a spinning-band fractionating column was equipped witha magnetic stirrer, nitrogen inlet and dropping funnel. The equipmentwas flame-dried and cooled; then 15 ml. of oxalyl chloride and 75 ml. ofanhydrous diethyl ether were introduced into the flask at ambienttemperature under positive nitrogen pressure. To this a solution of 30g. of 4 amino-2,2,5,5-tctrakis(trifiuoromethyl)-3-imidazoline dissolvedin 100 ml. of ether was added over 30 minutes with vigorous stirring.After stirring an additional 20 minutes, the ether was removed bydistillation at a moderate rate and the residue distilled at 75 mm. Theproduct, 4 isocyanato 2,2,5,5 tetrakis(trifluoromethyl) 3-irnidazoline,B.P. 78 C. (75 mm.), 25.7 g., was collected in oven-dried vials (as itreacts with moist air). The H nuclear magnetic resonance spectrum(n.m.r.) showed a singlet (broad) at 3.6 p.p.m. The F n.m.r. spectrumshowed a pair of septets (J =5) at +73.3 and +780 ppm. from externalFCCl at 56.4 mc.

Analysis.-Calcd. for C HN OF (383.12): C, 25.08; H, 0.26; N, 10.96.Found: C, 25.58; H, 0.77; N, 11.51.

The 4 amino 2,2,5,5 tetrakis(trifluoromethyl) 3- imidazoline startingmaterial for Example 1 was prepared by slowly distilling 3 moles ofhexafiuoroisopropylidenimine into a stirred suspension of 1 mole ofpowdered sodium cyanide in dirnet-hyl sulfoxide. An exothermic reactionoccurred and the rate of addition of the imine was adjusted so that thetemperature of the reaction mixture did not rise above 65 C. At the endof the addition, the homogeneous reaction mixture was cooled to 20 C.and poured into aqueous hydrochloric acid. The oil phase that separatedwas washed and dried, and there was obtained the white solidintermediate 4-[1-amino- 2,2,2 trifiuoro 1 (trifluoromethyl)ethylamino]2,2, 5,5-tetra'kis(trifluoromethyl)-3-imidazoline. This intermediate wasthen dissolved in concentrated sulfuric acid and the stirred solutionwas heated slowly to 150 C. and held at that temperature for 10 minutes.The solution was then cooled to C. and poured onto crushed ice. Theresulting white solid was filtered from the melted ice, washed, andrecrystallized from alcohol-water (1:2). This solid was4-amin0-2,2,5,S-tetrakis(trifiuoromethyl)-3-imidazoline and/or itstautomer 4-imino-2,2,5,S-tetrakistrifiuoromethyl imidazolidine.

Example 2.4-isocyanato-2,2,5,5-tetrakis(trifluoromethyl) -3-imidazolineA solution of 30 g. of4-amino-2,2,5,5-tetrakis(trifiuoromethyl)-3-imidazoline, or itstautomeric form, 4-imino-2,2,5,S-tetrakis(trifluoromethyl)imidazolidine, in 100 ml. of oxalylchloride was stirred at C. for 3 days, and then distilled. There wasobtained 26.05 g. (81%) of 4- isocyanato 2,2,5,5tetrakis(trifiuoromethyl) 3 imidazoline as a colorless liquid, B.P.67-67.5 C. (49 mm.).

4 Example 3.4 isocyanato 2,2,5,5tetrakis(chlorodifiuoromethyl)-3-irnidazoline Y =Y =Y =Y =Cl NH: NCO c Ccinema N 01000001 (CFQCDQO N HN-O(CFzCl)z HN-C(CF:C1):

With the use of apparatus and techniques described in Example 1, 3.4 g.of 4-isocyanato-2,2,5,5-tetrakis(chlorodifluoromethyl)-3-irnidazoline,B.P. 78 C. (1.5 mm.), was prepared by adding 5.0 g. of theamino-3-imidazoline dissolved in 20 ml. of ether dropwise over 30 min.to 3 ml. of oxalyl chloride dissolved in 10 ml. of ether. After stirringfor 20 min. at room temperature the reaction mixture was distilled. TheH n.m.r. spectrum of the product shows a single NH-band at 7 5.96 (CClThe F n.m.r. spectrum shows four complex multiplets at +2990, 3114, 3278and 3309 c.p.s. 'from external FCCl at 56.4 mc. The infrared spectrumshows a strong band at 2300 cm.- (4.3;i) characteristic of anisocyanate.

Ana!ysis.-Calcd. for C HN OCl F 21.89; H, 0.22. Found: C, 21.79; H,0.65.

The 4 amino 2,2,5,5 tetrakis(chlorodifiuoromethyl)-3-imidazolinestarting material for Example 3 was prepared by adding powdered sodiumcyanide portion-wise to a stirred solution of an equimolar amount of1,3-dichloro- 1,l,3,3-tetrafluoroisopropylidenimine (Example III of US.Patent No. 3,226,439) and dimethylformamide cooled to 0 C. As theaddition proceeded, the reaction mixture warmed slightly and the rate ofaddition was adjusted so that the reaction temperature remained below 10C. At the completion of the addition, the reaction mixture was pouredinto aqueous 10% hydrochloric acid to give crude 4 [1 amino 2 chloro 2,2difluoro 1 (chlorodifiuoromethyl)ethylamino] 2,2,5,5tetrakis(chlorodifiuoromethyl)-3-imidazoline as an oil. After washing,this intermediate was dissolved in 20% fuming sulfuric acid and thesolution was heated to 150 C. The solution was then cooled and pouredover crushed ice to give a solid which was collected on a filter, washedwith Water and dried. This product was4-amino-2,2,5,5-tetrakis(chlorodifluoromethyl)-3-imidazoline, and/or itstautomer.

Example 4.4-isocyanato-5,5-bis(chlorodifiuoromethyl)- 2,2-bistrifiuoromethyl -3-imidazoline A. Powdered sodium cyanide, 6.53 g.(0.133 mole), was added portionwise over a period of 30 minutes to astirred solution of 33.0 g. (0.2 mole) of hexafiuoroisopropylidineimineand 39.6 g. (0.2 mole) of 1,3-dichlorotetrafluoroisopropylidineimine in150 ml. of dimethylformamide cooled to -30 C. The reaction mixture wasstirred for one hour at 30 and then warmed to 25 C. and mixed with 200ml. of 10% hydrochloric acid. The organic layer was washed twice withwater and then dissolved in 40 ml. of 20% fuming sulfuric acid. Thissolution was heated to 150 C. and then cooled and poured over ml. ofcrushed ice. The solid that formed was collected on a filter, washedwith water, dried and sublimed at C. (10 mm.). There was obtained 33.0g. of a mixture of imidazolines as a white crystalline powder, M.P.1l8l55 C.

B. A solution of 30.0 g. of the above-described mixture of imidazolinesin 100 g. of oxalyl chloride was stirred at 25 C. for three days andthen distilled. There was obtained (A) 9.10 g. of4-isocyanato-2,2,5,S-tetrakis(trifluoromethyl)-3-imidazoline, B.P.70.070.5 C. (48 mm.); (B) 9.02 g. of4-isocyanato-5,5-bis(chlorodifluoromethyl) 2,2bis(trifluoromethyl)-3-imidazoline as a colorless liquid, B.P. 104-105C. (48 mm); and (C) 8.65 g. of4-isocyanato-2,2,5,S-tetrakis(chlorodifluoromethyl)-3-imidazoline, B.P.l42144 C. (48 mm.).

The F n.m.r. spectrum of the sample of 4-isocyanato 5,5bis(chlorodifluoromethyl)-2,2-bis(trifluoromethyl)- 3-imidazolineindicates that this sample also contained a minor amount (89%) of theisomeric 4-isocyanato-2,2- bis(chlorodifiuoromethyl) 5,5bis(trifiuoromethyl)-3- imidazoline, for the sample had two absorptionsin the CF region: one multiplet at +76.0 p.p.m. (relative area 9l92%)and one multiplet at +71.2 p.p.m. (relative area 89%) from FCCl Theinfrared spectrum showed a strong band at 4.40 4 for NCO.

Analysis.Calcd. for C HCl F N Oz C, 23.10; H, 0.24; Cl, 17.05; F, 45.67.Found: C, 23.23; H, 0.57; CI, 17.07; F, 45.37.

The following table lists additional specific products of the inventionand the reactants from which they are prepared, e.g., essentially by theprocesses of Examples 1-4.

TABLE lsocyanate NCO ClCFz 0 01 3 0 N CFzOl HN-CCF NCO HCF:

OF3C N OFzH HNCCF3 The isocyanate products of this invention are usefulin various applications. More specifically, the compounds are useful formodifying polymers. The following Example A illustrates the modificationof polyvinyl alcohol by 4isocyanato-2,2,5,5-tetrakis(trifluoromethyl)-3-imidazoline:

Example A with ether and then with Water, and dried in air. There wasobtained 0.62 g. of white polymer insoluble in water. A flexible oilandWater-repellant film was pressed from the polymer at C. and 10,000 lbs.ram pressure. Such modified polyvinyl alcohol films are especiallyuseful as oiland water-repellent wrappings or coatings for manyarticles.

The isocyanate products of this invention are also useful as agents forwater-proofing paper. The following example illustrates this utility:

Example B A strip of ordinary filter paper was placed in a testtube anddried with a warm air stream. A sample of 4isocyanato-2,2,5,5-tetrakis(trifiuoromethyl)-3-imidazoline (Example 1)vapor at C. was placed in the tube to penetrate the filter paper. Oncooling, the paper so treated was rendered water-proof, while anotherstrip of paper, identical except for such treatment was wettedimmediately. The difference in results demonstrates the usefulness ofthese isocyanates as agents for water-proofing paper.

The products of this invention are also useful as intermediates for thepreparation of carboalkoxyiminoimidazolidines,carbamyliminoimidazolidlines and disubstituted ureas, as described in myabove-mentioned U.S. application Ser. No. 521,317.

Since obvious modifications and equivalents in the invention will beevident to those skilled in the chemical arts, I propose to be boundsolely by the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A compound of the formula NCO wherein Y Y Y and Y are alike ordiiferent and are selected from the group consisting of hydrogen,chlorine and fluorine.

2. The compound of claim 1 in which 4-isocyanato 2,2,5,5 tetrakis(trifiuoromethyl)-3-imidazoline.

3. The compound of claim 1 in which Y =Y =Y =Y =-Cl 4-isocyanato 2,2,5,5tetrakis(chlorodifluoromethyl)-3- imidazoline.

4. The compound of claim 1 in which Y =Y =-Cl, and Y =Y -F, 4-isocyanato5,5 bis(chlorodifluoromethyl)-2,2-bis(trifluoromethyl)-3-imidazoline.

References Cited UNITED STATES PATENTS 2,915,528 12/1959 Raifsnider260309.6

OTHER REFERENCES Speziale et a1.: Jour. Org. Chem, vol. 27, pp. 3742-431962) HENRY R. JILES, Primary Examiner. N. TROUSOF, Assistant Examiner.

